Monitoring Study On Surface Environmental Change Of Shuixigou Coal Fire In Southern Junggar Coalfield

Coal fire is a typical ecological environment issue associated with the coal mining process.Especially in Xinjiang region,this issue is feature with numerous fire sites,which not only burns up massive coal resources,but also leads damages to local environment.The present thesis focuses on the Shuixigou coal fire,by employed a comprehensive method,including the inversion of the Landsat and Sentinel remote sensing data to quantify the changes of surface temperature,surface vegetation coverage and surface subsidence for monitoring the evolution of coal fire.Results and conclusions from this research were obtained and reached as follows:(1)Using multi-temporal Landsat data,the changes of surface vegetation and surface temperature were retrieved,and then were classified into four levels,i.e.,the grade one(<20%),grade two(<40%),grade three(<60%),and grade four(<100%).Results show that the grade one and grade two were the dominant type of surface vegetation coverage during the period of 1998～2018 in this area which accounts for about 90%.The change of the surface temperature which has a fluctuation during this period indicates the process of the status change of coal fire.(2)Result from the GM(1,1)prediction show that the area of grade one and grade four vegetation coverage decreases with the increase of the high temperature area and low temperature area.The area of grade one in 2018 is 23.139 km~2,and it will be22.909 km~2 in 2038.(3)Result from the analysis of the D-In SAR data show that the surface subsidence of Shuixigou coal fire changed during the period from 2014 to 2017.The maximum the surface subsidence changed from the value of 9.591 mm to the value of-3.124 mm,and the minimum of the surface subsidence varied from-19.132 mm to-26.059mm.(4)Combined with the data of surface vegetation coverage,the data of surface temperature,and the data of surface subsidence,two types of zone(the gas-escaping channel and the air-taking channel)were determined.Results from the data of surface subsidence during the period of 2014-2017,and two type of zone changed with different trend during this period.The number of zones of low temperature area overlying the grade four surface vegetation coverage decreases during from 2016 to 2017,while the number of high temperature overlying the grade one surface vegetation coverage increases during the same period,and it accounts for the least number of it in 2015.(5)Based on the determined fracturing zone,the details of subsidence with two types of channels were retrieved further.Results show that the larger subsidence for these two types happened in March and May 2016 which is consistent with the total subsidence of Shuixigou fire area.The low temperature area decreases in 2016,while the high temperature area increases during the same period.And it is the same for the changes of the grade one and the grade four surface vegetation coverage respectively.